Traditionally, under normal daylight conditions, a weapon having both front and rear sights is aimed by aligning the front sight such that its top just exposes the point on the target where impact is desired, and by subsequently "bracketing" the front sight in the sight notch of the rear sight, while ensuring that the tops of both the front and rear sights are aligned in the same horizontal plane.
It is known to paint white dots onto the gun sights. Typically, two white dots are provided symmetrically about the sight notch of the rear sight, and a single white dot is provided on the front sight. Although these white dots are useful primarily in daylight, they have also been found to be of some assistance in aiming the gun in low light conditions.
Radioluminous gaseous tritium light sources are also known to be incorporated into gun sights so as to enhance target acquisition under low light conditions. The tritium light sources are housed in a bore or slit formed in the gun sights and are arranged so as to appear as illuminated dots. Painting of white circles around the light sources on the rearward looking faces of the sights is also known, with the aim of providing an appearance in daylight similar to the appearance of the sights in low light conditions. A disadvantage of this arrangement, however, is that a user has to become used to two different appearances of the sights as, in daylight, only `empty` white circles are visible, while, in low light conditions, only the light sources are seen.
Although tritium light sources are conventionally attached directly to the body of the sights, a radioluminous light source housed in a metal holder may be inserted via the holder into an appropriate bore formed in the body of a sight. The holder is fastened to the sight via a very thin layer of a flexible RTV silicone adhesive. A white circle may also be painted about the light source on the rearward face of the sight.
In this arrangement too, the sights have very specific and distinct daylight and low light appearances. In daylight, there appears a white circle having therein an `empty` metallic circle (defined by an exposed edge of the holder), while, in low light conditions, substantially only the tritium light source is visible. Accordingly, a marksman must become proficient at using both the circles and the illuminated dots.
It would be advantageous to provide illuminated gun sights which have a generally similar appearance regardless of the ambient light level.
A further disadvantage in the conventional use of gaseous tritium light sources is the incompatibility of glass, which forms an outer casing of the light sources, and metal, from which the body of gun sights are made. None of the above-described prior art arrangements employing a radioluminous light source provides mounting thereof inside a metal housing in a manner that cushions a tritium light source therein against impact forces, vibration forces, and thermal expansion forces applied by the housing.
U.S. Pat. No. 5,065,519 describes a sight for a hand weapon which includes a sight blade, a bore located in the sight blade, and a self luminous capsule located in the bore for providing night sighting. The self luminous capsule has a generally circular light transmitting end which is located concentrically within said bore so as to define therewith an annular cavity surrounding said light transmitting. A substantially white material is provided within the annular cavity so as to define a white ring, thereby to provide improved day sighting.
U.S. Pat. No. 3,641,676, entitled "Radioluminous Gunsight and Method" discloses a gun sight coated with a radioluminous material so as to render the sight visible in low light conditions. The radioluminous material is applied in the form of a coating to selected surfaces of the gun sight. The radioluminous material is applied either directly to a gun sight, or is mounted thereon via a housing containing an amount of the radioluminous material.
U.S. Pat. Nos. 3,914,873 and 3,698,092 relate to electrically powered illuminated gun sights.
The following publications relate generally to gun sights: U.K. Patent No. 125,052 and U.S. Pat. Nos. 795,584 1,363,553 and 1,982,058.
The following publications describe chemical light sources: U.S. Pat. Nos. 3,316,109; 3,342,743; 3,366,573; 3,436,242; 3,456,043; 3,701,900; 3,706,543; 3,908,055 and 4,020,203.